Suction electrode



April 1959 R. H. KRUSE 2,880,729

SUCTION ELECTRODE Filed May 3, 1957 INVENTOR p/MPH A4904:

United States Patent M SUCTION ELECTRODE Ralph H. Kruse, Pelham, N.Y.

Application May 3, 1957, Serial No. 656,862

5 Claims. (Cl. 128-404) This invention relates to suction electrodes for making electrical contact with the body of a patient that is particularly useful in connection with electrocardiographic and other similar equipment.

Suction electrodes heretofore proposed for use in connection with electrocardiographic equipment have not been found entirely satisfactory for a number of reasons including complexity of structure and the difficulties entailed in maintaining the desired degree of cleanliness. In the use of suction electrodes, the surface of the skin to which the electrode is to be applied is usually rubbed with a slightly abrasive conducting jelly to insure low electrical resistance and to make good contact with the body. When a suction electrode is applied to the contact area, particles of the electrode jelly are often drawn into the electrode structure and this material must be removed frequently for obvious sanitary reasons and to prevent corrosion of the electrode. With known devices, this accumulation within the electrode is difficult and time taking to remove and frequently cannot be accomplished without the expenditure of excessive time and effort. If the electrode jelly is not completely removed, objectionable corrosion of the electrode results, producing high resistance and parasitic currents.

The above and other difiiculties are overcome with this invention which provides an improved electrode characterized by its small size, simplicity, ease of cleaning, dependability and ease of application to obtain a stable low impedance coupling with the skin.

Another object of the invention resides in a novel and improved suction electrode wherein the suction pressure is controlled to minimize discomfort to the patient and at the same time afford a constant relatively low impedance connection.

The above and other objects and advantages will become more evident from the following description and accompanying drawings forming part of this application.

In the drawings:

Fig. 1 is a side elevational view in partial section of one embodiment of the invention; and F Fig. 2 is a bottom view of the embodiment shown in As pointed out above the suction electrode in accordance with the invention provides a stable low impedance contact with the body, can be quickly and completely cleaned for sanitary and operational reasons and affords means for limiting the suction to avoid unnecessary patient discomfort. The ease with which an electrode may be completely and thoroughly cleaned is important not only because the time and effort that may be saved but also because of inaccuracies produced by reason of parasitic voltages resulting from corrosion. In the application of a suction electrode to a patients body, the area to which the electrode is to be applied is rubbed with a conductive jelly containing conductive salts. This material is frequently drawn into the inside of the electrode during use and the metal salts produced by resulting corrosion cause parasitic voltages that will adversely affect the accuracy 2,880,729 Patented Apr. 7, 1959 of the measurements made under such conditions. Through a novel arrangement of elements including a tubular contact member and a cooperating bulb, internal surfaces of the structure are readily and easily accessible, without dismantling the device, for thorough and complete cleaning. Moreover the avoidance of all restrictions eliminates the development of high velocity air streams that reduces the quantity of jelly that will be drawn into the electrode itself. In addition to the improved operation and stability of the invention, the coordination of the electrode elements enables the suction to be limited to a predetermined maximum to minimize patient discomfort and at the same time attain low contact resistance.

Referring now to the drawings illustrating one embodiment of the invention, the suction electrode includes a tubular member 10 preferably of German silver or other similar material. The wall of this cylindrical or tubular member should be made thick enough to provide suflicient rigidity and the internal surface should preferably be free of discontinuities such as grooves and the like. While the physical size of the member 10 may vary over wide ranges it is preferably made with an internal diameter large enough to facilitate cleaning and with a small length to diameter ratio.

The upper portion of the tubular member 10 is provided with a slightly reduced section 12, the upper edge of which has a peripheral rib or head 13 extending outwardly from the tubular member. This bead cooperates with the rubber bulb 14 to assist in holding the latter when cemented in place on cylindrical member 10. The neck 15 of bulb 14 tightly engages and is cemented to the reduced section 12 of the tubular member 10 and the body of the bulb 14 is generally spherical in contour curving outwardly from the neck and then inwardly to provide a flattened top section 16.

The electrode thus far described provides a convenient structure that may be easily applied to the patients body and through proper proportioning of the cooperating elements excessive suction is avoided and a stable low impedance contact is obtained. While depression of the bulb may be accomplished in any convenient manner, maximum suction will be obtained by gripping the electrode between the first and second fingers of the hand and depressing the bulb by applying thumb pressure to the flattened bulb top until it contacts the upper edge of the cylindrical section 10. By coordinating the volume and stiffness of the bulb with the volume of the tubular member, when the electrode is placed against the body of the patient and the pressure on the bulb is released the electrode will remain firmly in contact with the patients body without producing undue discomfort and skin irritation.

Another important consideration in the design of electrodes of this type is the generation of so-called stray potentials which often occurs where dissimilar metals or alloys are joined. In electrocardiographic equipment the potentials to be detached are small and it is therefore essential that these contact voltages be eliminated or maintained at an absolute minimum. This has been accomplished with this invention by the utilization of a terminal 17 preferably formed of identical material as the tubular member 10 and attached to the tubular member by soldering or other similar procedure to form a secure connection. While a variety of metals can be utilized for this purpose it is preferable to form the tubular member 10 and the terminal 17 of German silver and attach the terminal to the tubular member by the use of silver solder. In order to facilitate the attachment of a connecting lead to the terminal 17 the latter is provided with a transverse opening 18 and a German silver thumb screw 19 threadably engaging the terminal and adapted to intersect the opening 18. The outer end 20 of the terminal 17 may u be crimped after the insertion of the thumb screw in order to prevent its removal.

While only one embodiment of the invention has been illustrated and described it is apparent that changes, modifications and alterations may be made without departing from the true scope and spirit thereof as defined by the appended claims.

What is claimed is:

1. A suction electrode comprising a cylindrical contacting member of conductive material, an electric terminal secured to and extending from the wall of said cylindrical member at a point adjoining one end thereof, said cylindrical member having a section of reduced outside diameter adjoining the other end, an outwardly extending peripheral head on said other end, and a bulb closing said other end, said bulb having a cylindrical portion engaging said reduced section of the cylindrical member and an upper curved portion integrally formed with said cylindrical portion and terminating in a flattened top portion.

2. A suction electrode comprising a cylindrical contacting member of conductive material having an opening of substantially uniform area extending therethrough, a bulb of resilient material closing one end of said cylindrical member, said bulb defining a space having a volume slightly greater than the volume defined by said cylindrical member and terminal means connected to said cylindrical member at a point adjoining the top end thereof.

3. A suction electrode comprising a cylindrical member of conductive material having an opening of substantially uniform area extending therethrough, electric terminal means fixedly secured to said terminal member at a point adjoining one end thereof, a bulb of resilient material closing the other end of said cylindrical member, said bulb defining a space having a volume slightly greater than the volume defined by said cylindrical member, the length of said cylindrical member being substantially equal to its internal diameter.

4. A suction electrode having a bulb of resilient material and rounded configuration with an opening therein of a diameter at least approximating the maximum internal diameter of the bulb, a cylindrical contact member formed of an electrical conducting material fixed in said opening and having substantially uniform internal configuration throughout its length, the outside diameter of said contact member being at least as large as the diameter of said opening and an eletcrical connecter fixedly secured to said member, the inside diameter of said member being slightly smaller than the outside diameter and large in comparison to the Wall thickness.

5. A suction electrode comprising a cylindrical contact member formed of electrical conducting material and having substantially uniform internal diameter throughout its length, said inside diameter being large in comparison to the Wall thickness of said member, a bulb of resilient material and rounded configuration having an opening therein approximating the internal diameter of the bulb, an electrical connector fixedly secured to said member and means surrounding and extending from the opening in said bulb for securing it to and closing one end of said contact member whereby the inner surfaces of the bulb and contact member form a substantially smooth configuration with all portions of said surfaces being readily accessible for cleaning With the bulb in position on said contact member.

References Cited in the file of this patent UNITED STATES PATENTS 839,649 Roth Dec. 25, 1906 2,580,628 Welsh Ian. 1, 1952 FOREIGN PATENTS 18,973 Great Britain Aug. 12, 1910 

